1. Field of the Invention
The present invention relates to anchors for off-shore facilities, such as drilling rigs. More particularly, the present invention relates to a vent cap system for a suction pile. Even more particularly, the present invention relates to a vent cap system with alignment for opening and closing in any orientation and with a verifiable seal.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
A suction pile (also known as a suction caisson, a suction anchor, and a suction bucket) is used to moor a subsea drilling rig to the ocean floor. The suction pile is attached to the ocean floor, and rig structures are anchored to the attached suction pile. The suction pile is comprised of a generally tubular body, dropped into the water and floated down to the ocean floor. The open end of the tubular body embeds into the ocean floor, like an upside down bucket faced down in the soil. There is a closed end of the tubular body with a vent hatch. The vent hatch has an opened position and a closed position, and a remote operated vehicle (ROV) is used to move the vent hatch between these two positions. The opened position is used during deployment to the ocean floor, with water flowing through the tubular body by the vent hatch. Once landed, tubular body self-embeds into the ocean floor by sheer weight and momentum upon reaching the ocean floor. The suction pile is partially embedded when landed. For complete embedding, the closed position is used to seal the suction pile, so that air and water remaining in the tubular body are pumped out. An ROV can attach a hose to a suction port on the tubular body. Soil of the ocean floor is further sucked into the tubular body, solidly embedding the suction pile onto the ocean floor to a desired depth. The ROV removes hose and seals the suction port.
The completely embedded and at least partially filled suction pile forms a solid base for mooring a drilling rig structures. Suction piles as anchoring means for rigs and other oil and gas exploration installations are known. The suction pile may also function as a foundation for manifolds. A manifold can be set on top of the suction pile or a plurality of suction piles. Thus, the manifold is installed in a subsea location for access to multiple wells. The manifold on the suction pile can maintain multiple production flowline headers at a subsea location. For the suction pile as an anchor for a rig or foundation for a manifold, the vent hatch remains closed and sealed on the suction pile.
Variations of suction piles are known in the prior art. For example, United States Patent Publication No. 20060127187, published for Raines on Jun. 15, 2006, discloses a conventional anchor system with a variation on the suction pile structure. There is an elongated hollow anchor element releasably attached to an installation element.
The use of ROV technology to facilitate the embedding of a suction pile is also well known. United States Patent Publication No. 20090297276, published for Foo et al., on Dec. 3, 2009 discloses installation using the ROV instead of an aiming mechanism on the anchoring element of the suction pile. U.S. Pat. No. 6,719,496, issued to Eberstein on Apr. 13, 2004, also describes a system with ROV intervention to install a suction pile. The ROV with pump capability closes the flood valves on the top of the suction pile and attaches to the pumping port of the suction pile. The pump of the ROV operates to draw down the suction pile. The ROV disconnects from the pump port and connects a mooring line to second the load connection.
Variations of the vent hatch or vent cap of the suction pile are also known in the prior art. The primary type of vent hatch for a suction pile is the hinged cap. United States Patent Publication No. 20130220206, published for Mogedal et al on Aug. 29, 2013, shows a vent cap as a hinged cap with a frame to insure alignment of the cap plate over the hatch. Another type of vent hatch is the butterfly valve, shown in U.S. Pat. No. 6,719,496, issued to Eberstein on Apr. 13, 2004, with a cap plate swiveling over the hatch for opening and closure. Some vent hatches are combinations of the hinged cap and the butterfly valves, such as U.S. Pat. No. 6,322,439, issued to David on Nov. 27, 2001. The hinge elements transition between the traditional flipping hinged cap with the cap plate lifted from the hatch and the traditional butterfly vent cap with the cap plate swiveling over the hatch.
It is an object of the present invention to provide an embodiment of a vent cap system for a suction pile.
It is an object of the present invention to provide an embodiment of a vent cap having a closed position and an opened position.
It is still another object of the present invention to provide an embodiment of a vent cap being actuated between the closed position and the opened position by an ROV.
It is still another object of the present invention to provide an embodiment of a vent cap being actuated between the closed position and the opened position in both a horizontal orientation and a vertical orientation.
It is still another object of the present invention to provide an embodiment of a vent cap with alignment of the plate to seal the vent hole in any orientation.
It is yet another object of the present invention to provide an embodiment of a vent cap with improved handling for an ROV.
It is yet another object of the present invention to provide an embodiment of a vent cap with improved seals.
It is yet another object of the present invention to provide an embodiment of a vent cap with a means for verifying the seal of the vent hole.
It is yet another object of the present invention to provide an embodiment of a vent cap with replaceable parts.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.